In the present work, magnetically separable Fe3O4/ZnO/AgBr nanocomposites with different weight ra-tios of Fe3O4 to ZnO/AgBr were prepared by a facile microwave-assisted method. The resultant samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission elec-tron microscopy (TEM), energy dispersive analysis of X-rays (EDX), and vibrating sample magnetometery (VSM). Antifungal activity of the as-prepared samples was evaluated against Fusarium graminearum and Fusarium oxysporum as two phytopathogenic fungi. Among the nanocomposites, the sample with 1:8 weight ratio of Fe3O4 to ZnO/AgBr was selected as the best nanocomposite. This nanocomposite in-activates Fusarium graminearum and Fusarium oxysporum at 120 and 60 min, respectively. Moreover, it was observed that the microwave irradiation time has considerable influence on the antifungal activity and the sample prepared by irradiation for 10 min showed the best activity. Moreover, the nano-composite without any thermal treatment displayed the superior activity.